Stripper for rule die sets



Mmm

A TroR NE K litre Eidg Patented Aug. 7, 1962 tice 3,04,t)69 STRIPPER FOR RULE DIE SETS Milton Berlin, Forest Hills, and Lawrence M. Rheingold,

Baldwin, N.Y., assignors to Templet Industries, Incorporated, Brooklyn, NX., .a corporation of New York Filed Apr. 3, 1957, Ser. No. 650,485 4 Claims. (Cl. 253-123) This invention relates to rule die sets and more particularly, to a rule die set having self contained stripper elements for ydisengaging sheet metal stock and stamped elements from the male and female die members.

It has been found that automatic stripping devices can be used to great advantage in order to increase the rate of yoperation of rule die sets. Ordinarily, there is a tendency for the sheet metal stock material to cling to the male die member, while the stamped element becomes confined within the female die member, thereby requiring these elements and sheet stock to be disengaged before the next cycle can be initiated. While various types of resilient pads have been used to provide this stripping action, such have been subjected to severely high impact forces, deteriorating lubricants, and sharp metal edges, all of which have contributed to reducing the useful life thereof, thereby requiring periodic replacement and work stoppage. An object yof this invention therefore is to provide stripping apparatus for rule die sets that is simple in construction, efficient in operation, and which will overcome the a-forementioned difficulties.

Another object of the present invention is to provide a stripper assembly for female rule die members in which the stripping pressure may 4be selectively adjusted to provide an ejecting force of any desired strength, and which is completely confined within the cavity of the female die member.

Another object of the present invention is to provide a stripper assembly constructed of -a pair of metal plates having -a resilient pad or springs sandwiched therebetween, in which the distance between the plates may be selectively adjusted to control the thickness of the stripper assembly and `hence the loading of the resilient pad or equivalent sandwiched material.

A still further object of the present invention is to provide a stripper assembly for rule die sets that may be constructed of -rigid and resilient elements for-med directly by the die set with which it is to be associated, whereby substantial savings of time and money may be realized in the construction of the complete die set.

An additional object of the present invention is to provide a self contained stripper assembly 4that is removably supported within a female die rule 'which lfurther acts -as a sizing template to prevent over-compression of the cornpressible die blocks during the lock-up of the die set.

Another object 'of this invention is to provide a stripper assembly for female rule die members that facilitates the alignment of the die set through the use of associated shear-plate dowel pins that may be removably extended between the male and female member during the final lock-up of the die set.

Still a further object of the present invention is to provide a removable stripper assembly for female rule die members, one part of which conforms to the exact size and shape of the male die member and which thus automatically limits the application of lateral pressures to the female die member during subsequent lock-ups that would otherwise cause misalignment of the par-ts.

All of the foregoing and still further objects and advantages of this invention will become apparent from a study of the following specification, taken in connection with the accompanying drawing, wherein:

FIGURE 1 is an exploded perspective view, with parts broken away, of a rule die set made in accordance with the present invention;

FIGURE 2 is a top plan view of the male die member of the set shown in FIGURE l;

FIGURE 3 is a longitudinal cross sectional view taken along line 3-3 of FIGURE 2;

FlGURE 4 is a side elevational view of the stripper assembly, which in FIGURE 1, is shown in operative association with the female die member, parts being in section for clarity.

FIGURE 5 is a top elevational view of the stripper assembly shown in FIGURE 4;

FIGURE 6 is a 'bottom plan View of the female die member shown in FIGURE l, with the stripper assembly removed; and

FIGURE 7 is a longitudinal cross sectional view taken along line 7-7 of FIGURE 6.

Referring now to the drawing, and more particularly to FIGURES 1 to 3, thereof, a rule die set made in accordance with the present invention is shown to include a male die member and a female `die member. The male die member is provided with a platen 10 that is arranged to be secured to -a stationary base 15, such as by screws eX- tending through provided openings 11 adjacent to the periphery of lthe platen, The male die member or punch 12 is secured upon a central portion of the platen 10, such as by machine screws 13. Openings may be provided to support removable alignment pins i4 for facilitating the alignment of the die set during the locking-up of the male and female die members. A rectangular stripper plate 17 having a central opening corresponding substantially to the shape of the male die member I2, is disposed in circumposing engagement therewith to strip the sheet metal stock from the `male die member after each stamping operation. As is more clearly shown in FIGURE 3, the stripper 17 extends slightly -a'bove the top surface of the male `die member to assure the proper stripping of the sheet metal and to provide for a certain amount of permanent deformation of the stripper resulting from the constant imposition of very high compressive forces.

The female die member 20 is shown to include a first compressible die block 22 preferably, though not necessarily of ply wood, that defines a central opening. A second complemental compressible die block 24 also preferably, though not necessarily of ply wood, is disposed within the central opening and is in spaced relationship with the first die block 22. A plurality of steel rule elements are disposed between the first and second compressible die blocks so as to provide a female die member having the same configuration of and adapted to mate with the male die member. 12. For purposes of illustration, these steel rules are shown to be of rectangular configuration and include a pair of spaced parallel end rules 26 and a pair of spaced parallel side rules 27 ythat extend from the upper surface of the female die member 20, downwardly therethrough in overlying engagement with respect to the male die member I2. This entire die member 2li is secured between the various fixed and adjustable banks 29 of a chase that is secured to the retractable bolster B of a suitable press. By apply-ing a suiiicient compressive force to the first compressible die block 22 through the adjustable chase, the respective blades and compressible die blocks may be integrally secured together and thus are able to withstand tremendous forces.

The first or outer compressible die block 22 is substantially thicker than the inner compressible die block 24, whereby the inside surfaces of the blades 26, 27, together with the bottom surface of the second die block 24 define a downwardly opening recess,l within which a stripper assembly 30 is removablyreceived. As is more clearly shown in FIGURES 1 and 4, this stripper assembly Sil includes a metallic first upper base plate 33 and a similar second lower plate 35 of substantially greater thickness. A resilient pad or block 32, such as rubber or neoprene, is sandwiched between the upper and lower plates 33, 35. The plates and resilient pa-d are maintained in an assembled relationship with each other by means of a pair of machine screws 36 that extend freely through the upper base plate 33, the pad 32, and into threaded engagement within aligned threaded bores 37 in the lower plate 35. Thus, by adjusting the machine screws 36, the distance between the respective plates may be varied to alter the compression of the pad 32. The inner wall of the second complemental die block 24 is provided with cavities 38 that accommodate the upwardly protruding heads of the machine screws 36. This block 24 is also provided with a plurality of bores 41 through which machine screws 40 may be extended into threaded engagement with similarly threaded openings 42 in the rst upper base plate 33 of the stripper assembly, whereby the entire assembly 30 is releasably secured within the downwardly opening recess dened by the blades and die blocks.

In use, it is preferable to adjust the compression of the resilient pad 32 so that the bottom surface of the lower rigid plate 35 is in substantially the same plane as the edges of the blades 26, 27. Therefore, when the female die member is brought into engagement with the male die member, the resilient pad 32 is compressed during the resulting shearing action. Thus, upon the separation of the die members, the stripper assembly expands and automatically ejects the stamped element from the recess defined by the blades. Simultaneously, the annular stripper pad 17 associated with the male die member 12 disengages the stock material from the male die member 12, whereby all of the parts are ready for the next stamping operation.

While the lower rigid plate 35 must be maintained in substantially the same plane as the lower edges of the die rules, the pre-loading or pre-stressing of the .resilient pad may be varied to obtain any desired stripping force. This is achieved by predetermining the initial thickness of the intermediate resilient pad and by replacing the pad with another pad of diierent thickness or by adding resilient strips of material between the upper and lower rigid'plates 33, 35.- While a substantially solid pad of resilient material has been illustrated, it will be recognized that such pad may also be constructed of various types of metallic spring elements.

A punch 45 may also be associated with this die assembly and in such case is supported at `its upper end within an opening 46 in the complemental die block 24 and has a lower end that is within the lower limit of the blades 26, 27. The stripper assembly 3i) is provided with a centrally located bore 47 that is adapted to slidably receive the punch 45, whereby the proper operation of the punch and the stripper assembly is not impaired. The male die member l2 is also provided with a complemental opening 50 through which the lower end of the punch 45 is adapted to extend to pierce the stock material or work piece. The platen is provided with a simil-ar but tapered bore 5l to permit the removal of the punched material.

One of the novel features of the present invention is that the `die set may be used to literally build itself. Each of the stripper elements may be stamped directly by the assembled die set since it is intended that these elements conform exactly to the size and shape of the recess defined by the die rule. However, the edges of the resilient pad are slightly routed out to accommodate the expansion of the sides of the pad during the compression of the main body thereof. The edges of the lower rigid plate 35 are also polished to provide suicient clearance between the die rule so that the desired reciprocating perpendicular movement of the lower plate 3S relative to the upper plate 33 may be achieved during the use of the die set.

The stripper pad A17 of the male die member may also be formed by punching out the center of -a rectangular sheet.

The upper plate 33 of the stripper assembly acts as a backing plate or armor to shield the softer compressible material, from which the complemental die block is made, from otherwise damaging forces. This plate 33 also acts as a sizing template to prevent over-compression of the compressible die blocks during subsequent lock-ups of the die set. Thus, since the upper plate 33 conforms eX- actly to the size and shape of t-he male die member, it functions as an integral stop means and automatically limits the application of lateral pressures to the female die members during subsequent lock-ups that would otherwise cause misalignment of the parts. yIt will thus be recognized that a die set made in accordance with this invention can readily be removed from the chase and stored for prolonged periods, and then later assembled with a chase for use, any intervening distortion or warping of the die elements being readily compensated for through the use of the upper plate 33 as a sizing template. The stripper assembly also permits the location of alignment pins for setting up the die set. Furthermore, the rigid plates eifectively prevent the entrance of excess lubricating oil that would otherwise vdamage the pad, and contines the lubricant to the walls of the blades.

It will also be recognized that each element of the die set performs a special function. The rule or cutting blades are of high compressive strength to shear the work piece, the compressible die blocks secure the blades in place, the second lower plate 35 of the stripper assembly provides l-ateral stiffness to further reinforce the blades, and the first upper rigid plate 33 of the stripper assembly acts as a retainer for the resilient pad and provides for the adjustment of the compression of the stripper assembly.

While this invention has been described with particular reference to the construction shown in the drawing, it is to be understood that such is not to be construed as imparting limitations upon the invention, which is best defined by the :claims appended hereto.

We claim:

l. In a die set for stamping a shape from sheet metal: a male punch member having a certain shape, a female die member, means mounting said male punch member and said female die member in mutual alignment and for relative reciprocatable translatory movement toward and away from one another from spaced into `oper-ative telescopic engagement, said female die member including an outer compressible die block having a through opening therein of a closed shape congruous to and larger than the shape of the male punch member and an inner compressible die block within said opening, said opening and the outer periphery of said inner die block having complemental edge surfaces, plural rule die blades defining a constrictable closed shape the inner periphery of which is congruous to the shape of the opening in the outer die block and is adjustable by constriction to a shape matching the shape of the male punch member, said rule die blades being located between said complemental surfaces and being in contact therewith over the entire length of said surfaces, said rule die blades having longitudinal edge portions protruding beyond said die blocks and toward the male punch member, means pressing inwardly against substantially the entire outer periphery of the outer die block and placing the die blocks and shape dened by the rule die blades under compression to compress said die blocks against the entire surfaces on the opposite sides of the rule die blades so as to align the shape defined by the rule die blades with the male punch member and reduce the shape dened by the rule die blades to that of the male punch member, and a stripper assembly associated with the female die member and located within the closed shape defined by the rule die blades, said stripper assembly including a rigid member having an outer periphery coextensive with and complementary to the inner periphery of the closed shape defined by the rule die blades, said outer periphery matching the shape of the male punch member, said rigid member being .adjacent the .inner die block and adjacent the protruding portion of the rule die blades and limiting reduction of the shape defined by the rule die blades under compression to a shape matching the shape of the male punch member, said shapedrigid member being free of the rule die blades except for compression of said blades therearound, whereby the female die member may be decompressed and disassembled and subsequently reassembled with the shape dened by the rule die blades matching the shape of the male punch member by Virt-ue of the sizing action of the rigid member.

2. In a die set for stamping a shape from sheet metal: a male punch member having a `certain shape, a female die member, means mounting said male punch member and said female die member in mutual alignment and for relative reciprocatable translatory movement toward and away from one another from spaced into operative telescopic engagement, said female die member including an outer compressible die block having a through opening therein of a closed shape congruous to and larger than the shape of the male punch member and an inner compressible die block within said opening, said opening and the louter periphery of said inner die block having complemental edge surfaces, plural rule die blades deining a constrictable closed shape the inner periphery of which is congruous to the shape of the opening in the outer die block Iand is yadjustable by constriction to a shape matching the shape of the m-ale punch member, said rule die blades being located between said complemental surfaces and being in contact therewith over .the entire length of said surfaces, said rule die blades having longitudinal edge portions protruding beyond said die blocks and toward the male punch member, means pressing inwardly against substantially the entire outer periphery of the outer die block and placing the die blocks and shape dened by the rule die blades under compression to compress said die blocks against the entire surfaces on the opposite sides of the rule die blades so as to align the shape defined by the rule die blades with the male punch member and reduce the shape defined by the rule die blades to that ofthe male punch member, and a rigid member located within the closed shape defined by the rule die blades, said rigid member having an outer periphery coextensive with and complementary to the inner periphery of the closed shape defined by the rule die blades,

said outer periphery matching the shape of the male punch member, said rigid member being adjacent the inner die block and adjacent the protruding portion of the rule die blades and limiting reduction of the shape dened by the rule die blades under compression to 1a shape matching the shape of the male punch member, said shaped rigid member being free of the rule die blades except for compression of said blades th'erearound, whereby the female die member may be decompressed and disassembled and subsequently reassembled with the shape defined by the rule die blades matching the shape of the male punch member by Virtue of the sizing action of the rigid member.

3. A die set as set forth in claim 1 wherein the stripper :assembly further includes a rigid shaped plate slightly smaller further includes a rigid shaped plate slightly smaller than the shaped rigid member and supported for movement toward and away from the shaped rigid member, and resilient means interposed between the shaped rigid member and the rigid shaped plate.

4. A die set las set forth in claim 3 wherein the shaped rigid member constitutes a plate parallel to the movable shaped rigid plate.

References Cited in the file of this patent UNITED STATES PATENTS 110,762 Howe Jan. 3, 1871 389,763 Rock Sept. 18, 1888 548,101 Ward Oct. 15, 1895 828,226 Lorenz Aug. 7, 1906 964,061 Schwaber July l2, 1910 1,082,986 Wilder Dec. 30, 1913 1,701,546 Shaw Feb. 12, 1929 1,968,133 Engel July 31, 1934 2,417,414 Hornberger Mar. 18, 1947 2,821,871 Carno Feb. 4, 1958 2,850,096 Berlin Sept. 2, 1958 

